The microbiology of spent mushroom compost and its dust

Microorganisms in spent steamed mushroom compost and its dust were enumerated, isolated, and identified. Some phase II (indoor composting) compost samples were also examined. Steaming of spent compost resulted in a 70–76% reduction in microbial numbers. Total counts made with compost infusion agar were approximately two logs greater than those for nutrient agar.The most common bacterial isolate was Bacillus licheniformis. The most common actinomycete isolates were Streptomyces diastaticus and Thermoactinomyces vulgaris. Other actinomycete isolates included Streptomyces albus, Streptomyces griseus, Thermoactinomyces thalpophilis, Thermomonospora chromogena, and Thermomonospora fusca.The most common fungal isolates were Aspergillus fumigatus and Humicola grisea var. thermoidea. Other fungal isolates included Aspergillus flavus, Aspergillus nidulans, Aspergillus terreus, Aspergillus versicolor group, Chrysosporium luteum, Mucor spp., Nigrospora spp., Oidiodendron spp., Paecilomyces spp., Penicillium chrysogenum, Penicillum expansum, Trichoderma viride, and Trichurus spp.